POSTURAL STABILITY AND FALLS RISK IN THE ELDERLY IN BIODEX BALANCE SYSTEM: A RELIABILITY STUDY

Abstract

Background: The Biodex Balance System (BBS) platform is an important tool for assessing postural stability and risk of falls in the elderly. The objective of this study was to evaluate the inter-rater and test-retest reliability of the postural stability measures and the agreement of the identification of the risk of falling of the elderly in BBS. Methods: methodological study approved by ethics committee (n=34 elderly). The elderly were assessed in the Falls Risk (FR) and Postural Stability (PS) protocols. The platform was unstable in the FR (level 6-2, three repetitions of 20s). The stability was evaluated with and without visual feedback and with closed eyes in the PS (level 4, a repetition of 20s for each visual condition, unstable and stable platform). The elderly were assessed in two days. On the first day two evaluators assessed for inter-rater reliability and concordance study. One of the examiners re-evaluated the elderly after nearly one week to study test-retest reliability and agreement. Results: The FR measurements of the two evaluators were significantly different. The inter-rater interclass correlation coefficient (ICC) ranged from 0.48 to 0.71: very good reliability with unstable surface and good to very good reliability with stable surface. The ICC test-retest ranged from 0.64 to 0.91, featuring very good to excellent reliability. Moderate test-retest agreement (Kappa=0.529, p=0.002) and poor inter-rater agreement (Kappa=0,368, p=0,013) were found. Conclusions: the measures of postural stability and risk of falls in the elderly in BBS are reliable. Familiarization with the instrument may have improved retest performance evaluations.